In the related art, work cells are used to produce welds or welded parts. There are at least two broad categories of work cells, including robotic work cells and semi-automatic work cells.
In robotic work cells, the scheduling and performing of welding operations is largely automated, with little operator involvement. Thus, these cells generally have a relatively low labor cost and a relatively high productivity. However, their repeating operations cannot easily adapt to varying welding conditions and/or sequences.
In contrast, semi-automatic work cells (i.e., work cells involving at least some operator welding) generally provide less automation vis-à-vis robotic work cells, and accordingly have a relatively higher labor cost and a relatively lower productivity. Nevertheless, there are many instances where using a semi-automatic welding work cell can actually be advantageous over robotic work cells. For example, a semi-automatic welding work cell can more easily adapt to varying welding conditions and/or sequences.
Unfortunately, when welding more complex assemblies in related art semi-automatic work cells, multiple different welding schedules are often required for different types of welds on different parts of an assembly. In many systems, when a different welding schedule must be utilized, the operator is required to stop welding operations and manually adjust the output of the semi-automatic equipment according to the new schedule. In some other systems, this manual adjustment is eliminated by storing particular schedules in the work cell. Nevertheless, even in such systems, the operator still needs to cease welding operations and push a button to select the new welding schedule before he may continue welding.
Neither of these practices for setting a different welding schedule is particularly efficient. Thus, in practice, the number of welding schedules used in a semi-automatic work cell is often reduced in order to eliminate the need for constant adjustment of the output of the semi-automatic equipment. While this reduction of welding schedules makes the overall operation easier for the welder, the forced simplification of this approach can lead to reduced productivity and lower overall quality.
Additionally, when abiding by strict quality control specifications, it is sometimes necessary to perform welds in a specific sequence, verify that each weld is performed with a given set of conditions, and monitor the output of the equipment during the welding operations. In a robotic work cell, these requirements are easily fulfilled. However, in a semi-automatic work cell, these requirements are susceptible to human error, since the operator must keep track of all of these aspects in addition to performing the welding operations themselves.
An illustrative example of the above problems is shown in the related art semi-automatic welding method diagrammatically represented in FIG. 1. In this method, each of the various scheduling, sequencing, inspection and welding operations are organized and performed by the operator (i.e., the welder) himself. Specifically, the operator begins the welding job at operation 10. Then, the operator sets up the welding equipment according to schedule A, at operation 20. Next, the operator performs weld #1, weld #2, and weld #3 using welding schedule A at operations 22, 24 and 26. Then, the operator stops welding operations and sets up the welding equipment according to schedule B at operation 30. Next, the operator performs weld #4 using welding schedule B at operation 32. Then, the operator checks the dimensions of the assembly at operation 40, and sets up the welding equipment according to schedule C at operation 50. Next, the operator performs weld #5 and weld #6 using welding schedule C at operations 52 and 54. After the welding operations are completed, the operator visually inspects the welded assembly at operation 60, and completes the welding job at operation 70.
Clearly, the method shown in FIG. 1 depends on the operator to correctly follow the predefined sequencing for performing welds and inspections, to accurately change between welding schedules (such as at operation 30), and to perform the welding itself. Errors in any of these responsibilities can result either in rework (if the errors are caught during inspection at operation 60) or a defective part being supplied to the end user. Further, this exemplary semi-automatic welding method hampers productivity, because the operator must spend time configuring and reconfiguring weld schedules.
The above problems demand an improvement in the related art system.